Interlocking system for railroads



Fb. 23, 1932. LARKIN 1,846,494

INTERLOCKING SYSTEM FOR RAILROADS Filed July 8, 1929 A i! MM ZATTbRNEY Patented Feb. 23, 1932 ETE FATiEhiT QFFECE YORK; AGNES M. LARKIN, ADMINISTRATRIX OF ASSZGNUE TO GENERAL aArLwAY SIGNAL COM- INTERLOCKING SYSTEM FOR RAILROADS Application filed July 8, 1929. Serial No. 376,577.

This invention relates to power interlocking systems for railroads, and more particularly to means for safeguarding the power operation of facing point switches, so as to prevent improper operation during movement of a train over a switch.

In accordance with the present invention, it is proposed to provide a suitable train stop device near each power operated switch, and

L organize the control devices and circuits for the power operating means of the switch, in a way so that the switch can not be operated unless said tram stopping device is 1n its active stopping condition. More specifically, the invention contemplates a lever lock and direct power controlling device, which are governed by the condition of the train stop device, as well as the condition of the track circuit adjacent the switch points.

The various advantageous "features charac terizing the invention will be in part pointed out, and in part apparent, as the description progresses.

One specific embodiment of the invention is illustrated in the accompanying drawing in 1 a simplified and diagrammatic manner, more with the object of making it easy to understand the nature of the invention, than for the purpose of illustrating the specific construction of the devices preferably employed in a practical application of the invention.

The invention in general consists of a novel combination or organization of control de vices and circuits, and may be applied to various types of power interlocking, and modiiied or extended to apply to the diiferent conditions encountered in practice, so that it should be understood that the particular embodiment of the invention herein shown and described is merely typical or illustrative.

Referring to the accompanying drawing, there is illustrated diagrammatically typical layout for a single facing point switch, with a so-called two-arm signal, illustrated as a color light signal, protecting traific over the switch from left to right, in the direction indicated by the arrow. The track is divided by insulated joints in the usual way in accordance with standard practice to provide a detector track circuit section A adjacent the switch, and another track circuit section B beyond the switch up to the next block signal SG Another track circuit section C, in advance of the signal SG is also shown to make clear the control circuits preferably employed for the train stop device. Each of these track sections A, B, and C is provided with a suitable normall 1 closed track circuit, comprising a source of current (not shown), and track relays AT, BT, and CT. The circuits for controlling the indications of the signals SG and SG may be of any one of the various well known types; and since these circuits do not specifically form a part of the invention, they have not been illustrated.

It is contemplated that the points of the switch SW will be operated and locked by a suitable power operated switch machine, controlled by a manually operable lever in a distant tower, with the usual provisions for iechanical interlocking between levers governing other conflicting switches and signals, approach locking and other expedients, in

accordance with recognized practice. In the form of the invention shown, the switch machine SM, operating and locking the points of the switch SW, is assumed to be of the electrical type, such as shown for example in the patent to W. K. Howe, No. 1,466,903, dated September 4, 1923. The lever L, and associated parts for controlling the operation of this switch machine in accordance with the well known system of dynamic indication electric interlocking, is shown diagrammatically and comprises a slidable bar 5, provided with an operating handle 6, a cam slot 7 for driving a vertical tappet bar 8 of the mechanical interlocking, indication mechanism of the well known type, including in the patent to N. K. Howe,

a. latch and dog released by the energization of the indication magnet I, and force drop lever lock of the usual construction, including acoil 9 and latch contact 10. The lever bar 5 is connected to and operates contact blocks engaging pairs of contact springs 12 15, in the usual way. Associated with the lever L is indication selector IS, of the type as shown and described, for example, No. 1,550,611, dated August 18, 1925, said indication selector comprising normal and reverse coils 16 and 1'? and a movable contact arm 18 arranged to electrically connect a long contact 19 with two short contacts 20 and 21 respectively. Also associated with the lever is a cross protection relay CPR, shown diagrammatically, which is constructed and operates in the manner shown and described, for example, in the patent to VJ. S. Henry, No. 1,163,14J', dated December '7, 1915.

The invention contemplates a suitable train stop system, comprising a track device operable or controlled to either an active stopping position or condition, and an inactive or clear position or condition, together with suitable means for closing contacts if the track device of the train stop system is in its active stopping condition. In the embodiment of the invention shown, it is assumed that this train stopping system is of the well known mechanical trip type, such as now in use in the subw ys in New York city. This type of automatic train stop is familiar to those skilled in the art, and com prises a trip on the track, movable by an electric motor or pneumatic means, from a raised position, to which the arm is biased, to a lower position. This trip, when raised, engages suitable angle cocks or trip switches on the train, so as to apply the brakes automatically, each car of the multiple-hint electrically propelled trains, usually used with this type of automatic train stop system, ing equipped with such angle cocks or trip switches. Any other suitable type of train stopping system may be employed in accort ance with this invention.

In the accompanying drawing, the trip or train stopping track device ST is shown con-- ventionally, and is located adjacent to the signal SG. This trip ST is provided with contacts 2 1:, closed only when the trip is in the raised or stopping position, as shown. The operating circuits for the trip ST, being in accordance with well known practice, are not shown; but in order to make clear the way in which the usual retaining circuits for this trip ST are organized to carry out the invention, the control circuits for the holding coil 25 (shown diagrammatically) have been illustrated. The trip ST is provided with contacts 26 in the energizing circuit for the holding coil 25, said contacts 26 being closed only when the trip is in its inactive lowered position.

For simplicity in illustration, many of the circuits on the accompanying drawing are shown as terminating at B and C, which indicate the opposite terminals of a suitable battery, transformer, or other source of current.

In the tower are relays ATR and BTR directly controlled by the track relays AT and ET by circuits readily traced on the drawing, and serve to repeat these track relays.

liese repeater relays ATR and BT13 may of course be omitted, and the circuits controlled thereby taken directly throu h contacts on the respective track relays AT and BT, if desired, and if such contacts are available. These track relay repeaters ATR and BTR, together with contact 24 of the trip ST, control an energizing circuit for a relay LR in the tower, which may be traced as follows :starting B, contact 24c, wires 30 and 31, front contact 32 of the relay BT11, wire 33, front contact 3d of relay ATR, wires and 86, relay LE, to C.

Thus, the relay LE, conveniently termed a lock relay, energized, providing the trip ST is in its raised stopping position and the two track sections A and B are not occupied.

The front contact 37 of the locking relay LR controls the energizing circuit, readily traced, through the lever lock coil 9 and latch contact 10, so that the lever lock can not be released, if the relay LR is deenergized. A lamp 38, in multiple with the lever lock coil 9 and latch contact 10 serves to indicate to the operator whether or not the lever can be unlocked.

The other front contact 40 of the lock relay LR is included in the main power suppl connection from the battery ll to the contacts of the lever L, so that when the relay LR is deenergized, and its front contact a0 is open, power can not be supplied through the lever L to the switch machine SM.

Considering now the functions and mode of operation of the interlocking system or": this invention, assuming that the operator wishes to shift the switch SlV from normal position shown to the reverse position, he operates the signal lever (not shown) in the usual way, so as to cause the signal SG to indicate stop, and the trip ST to assume the raised stopping position, if not already in that condition. This releases the mechanical locking holding the lever L. Upon closing of the contacts 2 1, if there is no part of a train on either of the track sections A or B, the lock relay LR is energized, lighting the lamp 238 By closing the latch contacts 10, the operator may energize the coil 9 of the electric lever lock, releasing the lever, so that it may be pulled to the reverse indication position, provided there is no conflicting route estabwires 44 lished and the mechanical locking permits such movement.

This movement of the lever L to the reverse indication position, the relay LR being energized, establishes a reverse operating circuit for the machine SM which may be traced from the battery 41, wire 42, front contact 40 of relay LB, wire 43, safety magnet- S, and 45, coil 16 of indication selector IS, wire 46, contact springs 15 and con tact block 13, wire 47, to the reverse operating wire B, through the switch machine pole changer contacts and motor (not shown), and thence back to the battery 41 over the common wire CW. The energization of the coil 16 of the indication selector IS shifts the contact 18 to its dotted line position, connecting the contacts 19 and 20, so that when" the switch machine has completed its cycle of operation and generated a dynamic indication current in the usual way, the indication magnet I is energized to trip the indica tion mechanism and permit the lever L to be moved by the operator to the full reverse position. The operator may now clear the trip ST and the lower arm of the signal SG, permitting a train to advance and pass over the switch SW.

Since several cars of an pelled train are usually equipped with devices to cooperate with the trip ST, it is necessary to hold this trip in its clear position until the train has passed it; and in practice this is accomplished by a suitable form of so-called holding or retaining circuits. For example, according to one arrangement of said retaining circuits, the track trip is held in its clear position by a circuit through the back contact of the track relay next in advance of the trip and its signal. This arrangement is undesirable, because the trip may be held in the clear position by a failure of this track relay and allow trains to run by the signal at stop without being automatically stopped. In the ordinary series type of retaining circuit, the track trip is held in the clear position by a circuit including'in series the back contacts of the two track relays respectively in the rear and in advance of the trip and its signal. With this arrangement, the trip may assume the stop position as soon as the last wheels of the train have passed over the insulated joints at the trip. These types of retaining circuits are not suitable for use with the present invention, because one of the conditions under which the switch SW may be operated by power is that the trip ST is in its stop position; and it will be evident that it is important that this trip ST should not be allowed to resume its stop position, after having once been cleared to permit a train to pass, until this train has advanced beyond the switch points.

In accordance with this invention, the trip electrically pro- LE to permit power operation of even though either one of the track relay re- ST is held in its clear position until the train has cleared the track section A, so that the trip ST cannot assume its stop position and permit energization of the rela LR, until the train has cleared the switch XV. For this purpose the circuit for energizing the holding coil 25 of the trip ST is carried through the contracts 26 of said trip, over wire 50, through the back contact 51 of the track relay AT, wire 52, and then either along wire 53, through the front contact 54 of the track relay BT, wire 55, front contact 56 of the track relay CT to B; or through the back contact 57 of the track relay BT, to B.

By reason of this control circuit, when the train passes the trip ST and enters the track section A, the holding coil 25 is maintained energized through the back contact 51 of the track relay AT and the front contacts 54 and 56 of the track relays BT and CT. As the train advances and its front end enters the track section B, the holding coil 25 is still maintained energized through the back contacts 51 and 57 of the track relays AT and BT. When the rear end of the train has passed out of the track section A, and the track relay AT picks up, the circuit for energizing the holding coil 25 is broken, and the stop ST may assume its raised or stop position. It will be noted that both of the track circuits for the track sections A and B would have to fail, if section C be unoccupied. in order to hold the trip ST in the clear position, and such a failure of two adjacent track circuits is very remote, such failure due to the breaking down of the insulated joint-s between the two track sections being readily avoided by employing the same polarities of track circuit feed.

It is sometimes necessary for the operator to operate the switch under special emergency conditions, as for example, when there is a track circuit failure; and for this purpose an emergency release button ER is provided for energizing the relay LR, if the stop ST is in its raised or stop position. hen this emergency release button ER is operated to the position shown by a dotted line, a circuit for energizing the relay LR is established from B, through contacts 7 wires 30 and 58, contacts of the button ER, wires 59 and 36 of the relay LE, to C. In this way, the operator may energize the relay the switch,

peaters ATR or BTR is de-energized.

It should be understood that the operator will not operate this emergency release button ER, unless he is sure that there is no train standing over the switch SW; and if desired; this emergency release button may be sealed, or otherwise protected, so as to avoid its misuse.

It will be observed that the emergency operation of the switch machine,

by use of the 24 of the trip ST,

ice

button ER, is not possible unless the trip ST is in the stop position to close its contacts 2%. This prevents operation of trains over the switch while an emergency operation is taking place. In order that the operator may not carelessly or accidentally leave the button ER in its emergency release position, the circuit for signal SG is carried through the normally closed contacts of this button ER, as indicated, so that the operator, after he has once actuated the button ER, must restore it to normal before he can thereafter clear the signal SG and the trip ST. The specific control circuits for the signal SG, thus governed by the button ER may be anyone of the well known and usual types, and have not been shown in order to avoid complication in the illustration.

In case it becomes necessary to operate the switch machine under emergency conditions by means of the button ER, on account of a failure of one of the track relays AT or BT to assume its energized condition, and after the motorman of a train at the signal SG has operated a key along the track to clear the trip ST and thereby key-by the signal in the usual way, the trip ST is held in its clear position during the passage of the train through the track section A, by reason of the same circuits above explained. Consequently, during operation of the switch under emergency conditions, the trip ST cannot return to its stop position and permit a power operation of the switch, even with the aid or the buton ER, until the train has passed beyond the switch points.

From the foregoing, it can be seen that this invention safeguards the power operation of a facing point switch by requiring that a train stop device on the track, guarding movement over the switch, shall be in its stopping conditiombefore the control lever for the switch can be unlocked, and before power can be supplied to the switch machine. The power control, in addition to the lever lock, is preferably employed so as to take care of special conditions where the switch might otherwise be improperly operated. Since the switch cannot be operated unless the track device of the train stop system is active, and since this track device, when once cleared and the train has passed, it, cannot assume its stopping condition, until the train has cleared the switch, the operation of the switch is safeguarded in an efiicient and adequate manner, providing much more protection than is obtained with ordinary lever lock or track circuit power control.

What I claim is 1. In a system for controlling traffic on railroads, a power operated switch. a train stopping track device, and means for preventing operation of said switch unless said track device is in its active stopping condition.

2. In a system for controlling railway traffic, a track switch, a power operated switch machine for actuating said switch, a signal and a track trip governing traffic over the switch, and means for permitting operation of said switch machine only if said trip is in its stopping position.

8. In a trailic controlling system for railroads, a power operated switch, a control lever, a train stopping track device, and a lock for said lever releasable only if said track device is in its active stopping condition.

4. A trafiic controlling system of the type described comprising, a power operated switch, a track circuit adjacent to the switch, a train stopping track device, and means preventing operation of said switch unless said track device is in its active stopping condition and said track circuit is not occupied.

5. In a system of the character described, the combination with a power operated switch, a track circuit adjacent to the switch, and a train stopping device; of a relay for governing the operation of the switch and energized only if said track circuit is not occupied and also said train stopping device is in its active stopping condition.

(3. In a system for controlling railway trailic, a power operated switch, a control lever therefor, a track circuit adjacent the switch, a track trip governing train movement over the switch, a relay energized only if said t 'ip is in its stopping position and said track circuit is not occupied, and a power supply circuit for said switch machine closed only if said relay is energized.

7. A system for controlling the operation of track switches comprising, an electrically operable switch machine, a train control track device for at times producing an automatic brake application on a passing train, a lever in a tower for controlling the operation of said switch machine, and means in the tower responsive to the operating condition of said train control track device for governing the application of power to said switch machine.

8. In a system for governing railway traffic, a power operated track switch, a train control device governing movement of trains over said switch, means for preventing operation of said switch by power unless the train control device is in its stopping condition, and means for maintaining said train control device in its clear condition upon movement of the train thereby until it has passed beyond said switch.

9. In a system of the type described, a power operated switch, a track trip governing train movement over the switch, and operation of the switch track circuits near the switch, and means controlled by said track circuits for retaining said trip in the clear position until the rear end of a train has passed beyond the switch.

10. In a system of the character described, the combination with a power operated track switch and track circuits adjacent thereto, of a train central device governing train movement over the switch, means for permitting operation of the switch by power only if said train control device is in its stopping condition, and means controlled by said track circuits for maintaining said train control device in its clear condition upon movement of a train thereby until it has passed beyond said switch. In testimony whereof I afiix my signature.

JOHN J. LARKIN. 

